On 12/3/20 12:14 PM, Hans-Peter Nilsson via Gcc-patches wrote:
Belatedly, here's an updated version, using Martin Sebor's
suggested wording from
"https://gcc.gnu.org/pipermail/gcc-patches/2020-July/549580.html";.
I added two commas, hopefully helpfully. Albeit ok'd by Richard
Biener in
"https://gcc.gnu.org/pipermail/gcc-patches/2020-July/549922.html";,
better have this reviewed properly, including markup (none added).
Ok for trunk (gcc-11) and gcc-10?
Thanks for taking my suggestion!
These are just formatting nits but I would only further suggest
to enclose the name S (since it names a type) and the second
volatile in an @code{} directive (since it's a keyword).
(The volatile in volatile access is not one so it shouldn't
be formatted that way.)
Martin
---
We say very little about reads and writes to aggregate /
compound objects, just scalar objects (i.e. assignments don't
cause reads). Let's lets say something safe about aggregate
objects, but only for those that are the same size as a scalar
type.
There's an equal-sounding section (Volatiles) in extend.texi,
but this seems a more appropriate place, as specifying the
behavior of a standard qualifier.
gcc:
2020-12-02 Hans-Peter Nilsson <h...@axis.com>
Martin Sebor <mse...@redhat.com>
PR middle-end/94600
* doc/implement-c.texi (Qualifiers implementation): Add blurb
about access to the whole of a volatile aggregate object, only for
same-size as a scalar object.
---
gcc/doc/implement-c.texi | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/gcc/doc/implement-c.texi b/gcc/doc/implement-c.texi
index 692297b69c4..2e9158a2a45 100644
--- a/gcc/doc/implement-c.texi
+++ b/gcc/doc/implement-c.texi
@@ -576,6 +576,11 @@ are of scalar types, the expression is interpreted by GCC
as a read of
the volatile object; in the other cases, the expression is only evaluated
for its side effects.
+When an object of an aggregate type, with the same size and alignment as a
+scalar type S, is the subject of a volatile access by an assignment
+expression or an atomic function, the access to it is performed as if the
+object's declared type were volatile S.
+
@end itemize
@node Declarators implementation
